Package scale.alias

Provides alias analysis.

See:
Description

Class Summary

AliasAnalysis	A class for computing aliases among variables.
AliasVar	A class which maintains information about an expression (variable or access path) that may be involved in an alias.

Package scale.alias Description

Provides alias analysis.

The Scale compile may perform alias analysis either:

• interprocedurally
• intraprocedurally
• never

This analysis may be performed by:

• Bjarne Steensgaard's Algorithm
  • a rich points-to set describes the variables
  • interprocedural flow-insensitive analysis
  • almost-linear time complexity
  • linear space complexity
  • based upon type-inference methods
• Shapiro-Horowitz's Extension to Steensgaard's Algorithm
• a Simple Algorithm which uses a single points-to set

No alias analysis may also be selected in which case most Scale optimizations can not be performed.

Relevant Statements in Alias Analysis

   x = y
   x = &y
   x = *y
   x = op(y1, ... yn)
   x = allocate(y)
   *x = y
   x = ftn(f1, ..., fn) => (r1, ..., rm)
   x1, ..., xm = p(y1, ..., pn)

Storage Shape Graph

Bjarne Steensgaard, "Points-to Analysis in Almost Linear Time", Proceedings of the Twenty Third Annual ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages, St. Petersburg, FL, Jan 1996.